from numpy import *
import operator

def createDataset():
    group = array([[1.0,1.1],[1.0,1.0],[0,0],[0,1.0]])
    labels = ['A','A','B','B']
    return group,labels

def classify0(inX,dataSet,labels,k):
    dataSetSize = dataSet.shape[0]
    #（以下三行）距离计算
    diffMat = tile(inX,(dataSetSize,1))-dataSet
    sqDiffMat = diffMat**2
    sqDistances = sqDiffMat.sum(axis=1)
    distances = sqDistances**0.5
    sortedDistIndicies = distances.argsort()
    classCount = {}
    #（以下两行）选择距离最小的k个点
    for i in range(k):
        voteIlabel = labels[sortedDistIndicies[i]]
        classCount[voteIlabel] = classCount.get(voteIlabel,0) + 1
    sortedClassCount = sorted(classCount.items(),
    #排序
    key=operator.itemgetter(1),reverse=True)
    return sortedClassCount[0][0]
